Measurement Specialties 9116 - Manual (Page 55)

Pressure Systems, Inc. Model 9116 User’s Manual
Page 46 www.PressureSystems.com
DEFINE/CONTROL AUTONOMOUS HOST STREAMS (Command ‘c’)
Purpose:
Defines and controls the autonomous delivery of any of up to three concurrent
high-speed autonomous data streams to the host computer. Such data streams
may be delivered “continuously” without bound (i.e., until a command explicitly
stops them), or be delivered in a “limited” amount (until a pre-specified fixed
number of data packets have been sent). Each packet delivered may be
synchronized by a user-supplied “hardware trigger” or each packet may be
delivered periodically as synchronized by an internal software clock. These
concurrent host streams are an alternate method of acquiring/delivering data
rather than using the Read High-Precision Data (‘r’) command, the Read High-
Speed Data (‘b’) command or the many other special purpose read commands
(‘V,’ ‘a,’ ‘t,’ ‘m,’ and ‘n,’) for reading alternate data values.
Host data streams, once activated in a module, deliver a sequence of TCP/IP or
UDP/IP data packets autonomously to the host (i.e., without the host sending any
particular command to the module to request each packet).
Command “c ii[ dddd] ... ”
‘c’ is the command letter
‘ ii’ is a space + a sub-command index (augment code)
‘ dddd’ are one or more optional datum fields, each preceded by a space
character which are parameters that differ per augment code ii.
NOTE: all parameters are separated by a space.
Response
Depends upon particular sub-command (‘ ii’) sent. See below.
Autonomous
Packet
Depends upon the particular sub-command
(‘ ii’) sent. See below.
Description: The firmware of any module, once fully initialized, continuously scans and
converts data for all pressure channels at the highest possible speed. The result
of such scanning is a continuously updated EU data buffer, available to three
concurrent host data delivery tasks, or available to other standard data
acquisition commands in the module. Each host delivery task can grab
engineering-unit data values from the EU data buffer and deliver them to the host
in its own programmable data stream (a sequence of TCP/IP or UDP/IP packets
that autonomously arrive in the host, as long as the host has enough TCP/IP
buffering space to hold them).
WARNING: If these data streams are defined to occur at high rates, then each data
packet received by the host must be processed and disposed of in a timely
manner. NetScanner™ System modules are capable of generating autonomous
data faster than some “slow” hosts (or incapable software) can absorb.